ECU Failed in 2021 Tacoma Sport at 22k miles

Hey all, just wanted to share my experience with my 2021 Tacoma TRD Sport and see if anyone else has had a similar experience.

I purchased my 2021 Sport in April 2023 used with 7k miles on it. For the past few months it has felt a little sluggish on the acceleration, especially when speeding up to merge on a highway. It also feels a little jerky when trying to maintain speed at around 40/50mph. I did a bunch of forum reading and saw some other owners reported the same thing and most chalked it up to the nature of the truck. I was planning to live with it because its a small price to pay for such an awesome truck but made an appointment with the Toyota dealer for next week just in case. I wanted them to check on the transmission and torque converter.

While reading I found out about the ECT button and decided to test it out since I had never used it. I went for a quick 5 minute drive with the ECT engaged. Acceleration definitely felt more pleasant with it on and I figured I might use it when merging onto a highway.

One hour after this test drive I started my truck again and drove for a half mile before the dash lit up with a message "2WD-4WD Mode Change Malfunction - Visit your dealer" and the warning sign and 4 lo sign were flashing. I had not touched the 4wd switch since I last tested it a month ago. I drove another 2 miles at a very low speed before I parked it. I took it to the dealer this morning and they diagnosed it with a failing ECU. They asked me if I do any off-roading or driving in water, which I do not.

My questions are:

1. Could a failing ECU contribute to the sluggish acceleration behaviors I noted?
   
   
2. Could using the ECT for the first time since I owned the truck have caused this issue? Could it have caused a short or something like that?
   
   
3. Are there other factors that could have caused the ECU to fail that I should be concerned about? Could it lead to it failing again?
   

tldr: ECU failed on 2021 Tacoma Sport at 22k miles shortly after using the ECT for the first time.

Thank you!

 

^There are multiple ECUs in the vehicle. The dealer is likely talking about the 4WD ECU, which is separate from the powertrain control ECU which controls the engine and transmission.

I don't have much confidence in the dealer's ability to properly diagnose the issue. Is the dealer replacing the 4WD ECU under warranty?

 

Ahh okay. Good to know - thank you!
I did ask the tech for more information about the failure so he will probably clarify that once I hear back.

 

From what I know so far, this replacement is going to be covered under the warranty.